Tanshinone IIA contributes to the pathogenesis of endometriosis via renin angiotensin system by regulating the dorsal root ganglion axon sprouting

Abstract

Aims: Our study was designed to explore the function and mechanism of Tanshinone IIA in alleviating pain syndrome caused by endometriosis (EMs).

Main methods: Female Sprague-Dawley rats went through autotransplantation operation to establish EMs model. The rats were randomly divided into five groups: sham, model, positive, Tanshinone IIA (L) (3 mg/kg/d) and Tanshinone IIA (H) (12 mg/kg/d) group. Volume of ectopic endometrium was measured after 21 days of continuous administration. Serum estradiol (E2) was detected by enzyme linked immunosorbent assay (Elisa). The protein expression of angiotensinogen (AGT), renin (REN), angiotensin converting enzyme (ACE), angiotensin II (ANGII) and angiotensin II type 2 receptor (AT2) in the dorsal root ganglion (DRG) neurons were measured by immunohistochemistry and Western Blotting. The mRNA expression levels of AGT and ANGII were measured by Real-time polymerase chain reaction (PCR).

Key findings: Tissue measurements showed that tanshinone IIA significantly inhibited the growth of ectopic endometrium. Tanshinone IIA could improve the paw withdrawal threshold thus reducing the mechanical hyperalgesia of EMs rats. Moreover, Tanshinone IIA regulated the DRG renin angiotensin system (RAS) by reducing the protein expression of AGT, REN, ACE, ANGII and AT2 in DRG neurons. Furthermore, Real-time PCR results also showed that the mRNA expression levels of AGT and ANGII in the DRG neurons were decreased.

Significance: The Tanshinone IIA inhibitory effect on the EMs associated pain in EMs rats might occur through decreasing the expression of E2, ANGII and AT2, thus halting DRG sprouting and promoting hyperalgesia threshold.

Keywords: Angiotensin II; Dorsal root ganglion; Endometriosis; Estradiol; Renin angiotensin system; Tanshinone IIA.